This application claims the priority of German application 197 52 139.8, filed in Germany on Nov. 25, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a heat-transfer device for a motor vehicle with at least one collecting box divided by at least one lengthwise partition into at least two collecting chambers extending parallel to one another, and with a rib/tube block composed of a plurality of tubes and corrugated ribs, within the tubes each forming the same number of terminating channels for both collecting chambers.
A heat-transfer device of this kind is known from German Patent Document DE 44 32 972 A1. In this document, two collecting chambers are formed by a lengthwise partition in a collecting box of the heat-transfer device. A rib/tube block of the heat-transfer device has two rows of flat tubes parallel to one another, with one row of flat tubes being associated with one collecting chamber and the other row of flat tubes being associated with the other collecting chamber of the collecting box. The tube ends of the two rows of flat tubes that terminate in the respective collecting chambers are so designed that a sufficient space remains between the adjacent tube ends of a pair of flat tubes located one behind the other in the air through-flow direction that permits the lengthwise partition to be inserted between the respective tube ends. As a result of the special design of the tube ends, a sufficient space remains for inserting the lengthwise partition in the vicinity of the collecting box, although the flat tubes abut one another directly further along the rib/tube block. The bottom through which the tube ends of the flat tubes penetrate as well as the lengthwise partition and the flat tubes themselves are made of metal and connected with one another by brazing.
A similar heat-transfer device is known from German Patent Document DE 34 40 489 A1 which has flat tubes on one side provided with a water box. The ends of the flat tubes facing away from the water box are closed. Each flat tube has a separating rib that divides the flat tube into two flow channels, said separating rib being interrupted at a distance from the respective closed end of the flat tube, thus permitting a U-shaped flow reversal of the coolant.
A goal of the invention is to provide a heat-transfer device of the species recited at the outset whose design and manufacture are further simplified relative to the prior art.
This goal is achieved by virtue of the fact that the tubes are designed as multichannel tubes divided by at least one separating rib that runs lengthwise and is positioned at the level of the at least one lengthwise partition into a number of channels that corresponds to the number of collecting chambers, and in that the at least one lengthwise partition is provided at its lower edge facing the tube ends with recesses matching the spacing of the multichannel tubes, said recesses fitting over the separating ribs of the multichannel tubes in a shapewise flush fashion and being connected tightly with the outside contours of the tube ends. With the solution according to the invention, it is merely sufficient to provide a row of tubes to produce the desired number of flow channels. By providing the lengthwise partition with the recesses that fit flush over the separating ribs, a tight connection of the at least one lengthwise partition with the multichannel tubes is created that enables reliable separation of the collecting chambers from one another. If the collecting box is provided with a bottom through which the multichannel tubes project, the lengthwise partition also has its lower edge tightly connected with this bottom. In bottomless collecting boxes, in which the multichannel tubes are expanded to a flush block, the lower edge of the at least one lengthwise partition is shaped accordingly in order to produce a tight connection with these tube ends.
In certain preferred embodiments of the invention the multichannel tubes are designed as flat tubes and the separating ribs as lengthwise beads. This is an especially simple and economical design.
In certain preferred embodiments of the invention, the at least one collecting box is provided with a bottom which in turn is provided with a number of eyelets, openings or passageways that corresponds to the number of multichannel tubes, said eyelets, openings or passageways being provided at the level of the lengthwise beads of the multichannel tubes with tab-shaped rib segments that are applied flush. The lower edge of the lengthwise partition is provided in its segments between the recesses with profiles that terminate flush with an upper surface of the bottom between the eyelets, openings or passageways. This allows a tight connection between the bottom, the multichannel tubes, and the at least one lengthwise partition.
In certain preferred embodiments of the invention, the collecting box provided with the collecting chambers, the at least one lengthwise partition, the bottom, and the tube ends that penetrate the eyelets, openings or passageways are made of metal and tightly brazed to one another. This produces a wholly metal heat-transfer device that guarantees complete recyclability. The brazing of the individual metal parts of the heat-transfer device makes possible, with especially simple means, a tight and permanent connection between the parts.
In certain preferred embodiments of the invention, the flat tubes are sealed at their ends opposite the lengthwise partition, and the lengthwise beads terminate at a distance from the sealed tube ends, forming a U-shaped reversing section. As a result, a reverse flow is produced in each flat tube that permits arranging the connections for supplying and returning a cooling or heating circuit so that a collecting box can be eliminated in the vicinity of these tube ends.
In certain preferred embodiments of the invention, the flat tubes are pressed flat in the area of the sealed tube ends and shaped in such fashion that the tube ends project to one side at right angles. As a result, by simple means, a tight closure of the tube ends is produced. Preferably, this is accomplished by simple folding or by folding combined with subsequent bending into a U.
In certain preferred embodiments of the invention, the transverse extent of the reshaped tube ends of each flat tube corresponds to the spacing of the tube ends from one another. As a result, the ends of the bent tubes in the brazed rib/tube block directly abut the respective adjacent flat tubes, so that with a corresponding braze-plating of the flat tubes, brazing of these ends to the adjacent ends of the flat tubes can be achieved that permits a stable connection of all the tube ends on the side opposite the collecting box. As a result, the stability of the entire rib/tube block and hence of the heat-transfer device is increased while at the same time making it extremely simple to manufacture.